Most of the adjectival verbs in the Kathmandu and Dolakha dialects of Newar exhibit idiosyncratic phonotactic shapes, including rare disyllabic stems and heavy and nasalized rhymes. The same set of adjectival verbs exhibits irregular inflectional patterns in the derivation of lexical adjectives in Kathmandu Newar. Comparison of the modern forms of both varieties and Classical Newar suggests that we reconstruct a class of monosyllabic adjectives for Proto-Newar. In Classical and Kathmandu Newar, these adjectives received an /u/ augment; verbs were created with the infinitive -ye and the attendant Class III verb paradigm. By contrast, in Dolakha Newar the forms underwent a derivational process, probably originally compounding, with the verb yer- “come”. This process resulted in disyllabic stems which now follow regular inflectional patterns, except under negation. The incorporation of the old adjectives into the modern verbal systems thus represents a separate wave in the development of modern verbs in Newar.